Age Related Change in Mitochondrial Angiotensin System and Mitochondrial Decline

项目摘要 衰老和线粒体功能下降密切相关。线粒体功能障碍的主要迹象包括 增加了活性氧的生成，减少了每消耗O2产生的ATP分子，以及 细胞凋亡率增加。ATP的减少转化为细胞维护过程中能量的降低 包括有丝分裂和周转。我们最近报告了一种功能线粒体的鉴定 血管紧张素系统(MAS)，并发现衰老会影响关键的血管紧张素1和2的比率 线粒体上的受体(AT1R和AT2R)，AT1R阻断剂可以部分逆转这些变化 改善线粒体功能。重要的是，AT1R-/-小鼠的寿命在一定程度上提高了25% 通过增加线粒体的数量。增龄对线粒体(Mt)表达的影响 AT1R和mtAT2R及其对线粒体功能障碍的年龄相关性改变的贡献尚未得到证实 以前研究过的。新的初步证据表明，AT1R阻断老年小鼠可能会恢复衰老- 线粒体能量生产的相关下降，并通过改变P53-来提高吞丝效率 诱导蛋白(MIEAP)表达。我们假设与年龄相关的mtAT1R/AT2R比率的增加 通过增加活性氧(ROS)调节线粒体能量代谢的下降 受损线粒体的产生和受损的消除。为了检验这一假设，我们提出了一个 青壮年对照及氯沙坦治疗前后mtAT1R和mtAT2R的综合研究 (38个月龄)C57BL/6、AT1-/-和AT2-/-小鼠。将使用与年龄相关的心肌生物能量衰竭作为 研究mtAT1R和mtAT2R变化影响的模型如下提出的具体目标：1.确定 外周血管紧张素系统(PAS)和MAS的增龄性改变及其在改变中的作用 活性氮/氧物种ROS/RNS的产生，使用Q-PCR、蛋白质印迹、共聚焦和电子 显微镜。ROS/RNS的产生将在分离的心肌细胞和ALL的线粒体中进行量化 我们的动物小组使用特定的荧光探针。2.明确与年龄相关的变化的贡献 磁共振波谱和成像在PAS和MAS中对生物能量障碍的影响 基线和安慰剂或氯沙坦治疗四周后活体动物的心脏组织。Mas 将在所有动物的分离的心肌线粒体中研究对生物能量学变化的贡献。 组。3.研究PAS和MAS在线粒体生物发生、修复和修复中的作用 利用带有P53活性报告的心肌细胞系(H9C2)来测量 AT1R和/或AT2R过表达对MIEAP、氧化应激、线粒体DNA损伤和有丝分裂的影响 同样的结果也将在对照组和接受LOS治疗的年轻人和老年人(38个月大)之间进行比较。 C57BL/6、AT1-/-和AT2-/-小鼠。

Project Abstract Aging and decline in mitochondrial function are closely linked. Key signs of mitochondrial dysfunction include increased generation of reactive oxygen species, fewer ATP molecules produced per O2 consumed, and increased apoptosis. The reduction in ATP translates to lower energy for cellular maintenance processes including mitobiogenesis and turnover. We recently reported the identification of a functional Mitochondrial Angiotensin System (MAS), and found that aging impacts the ratio of key angiotensin type 1 and type 2 receptors in mitochondria (AT1R and AT2R), that AT1R blocking agents may partially reverse these changes and improve mitochondrial function. Importantly, AT1R-/- mice have an enhanced life span by 25%, in part through an increase in mitochondrial numbers. The effects of aging on the expression of mitochondrial (mt) AT1R and mtAT2R and their contribution to age-related changes in mitochondrial dysfunction has not been previously studied. New preliminary evidence suggests that AT1R blockade in old mice may restore the age- related decline in mitochondrial energy production and improve mitophagy efficiency via alterations in p53- inducible protein (MIEAP) expression. We hypothesize that an age-related increase in mtAT1R/AT2R ratio mediates declines in mitochondrial energy metabolism via increased reactive oxygen species (ROS) production and impaired elimination of damaged mitochondria. In order to test this hypothesis we propose a comprehensive study of mtAT1R and mtAT2R, in control and losartan (AT1R blocker) treated, young and aged (38-month old) C57BL/6, AT1-/- and AT2-/- mice. Will use age related cardiac muscle bioenergetics failure as a model to study the impact of changes in mtAT1R and mtAT2R following proposed specific aims: 1. To identify age-related changes in peripheral angiotensin system (PAS) and MAS and their contribution to altered reactive nitrogen/oxygen species ROS/RNS generation, using Q-PCR, western blot, confocal and electron microscopy. Generation of ROS/RNS will be quantified in isolated cardiomyocytes and mitochondria from all our animal groups using specific fluorescent probes. 2. To specify the contribution of age-related changes in PAS and MAS to bioenergetic dysfunction by magnetic resonance spectroscopy and imaging in the cardiac tissue of living animals at baseline and after four weeks of placebo or losartan treatment. MAS contributions to the changes in bioenergetics will studied in isolated cardiac mitochondria from all animal groups. 3. To investigate the role of the PAS and MAS on mitochondrial biogenesis, repair, and elimination by utilizing a cardiac cell line (H9C2) instrumented with a P53 activity reporter to measure the effects of over-expressing AT1R and/or AT2R on MIEAP, oxidative stress, mtDNA damage and mitophagy. Similar outcomes will also be compared between control and LOS treated, young and aged (38-month old) C57BL/6, AT1-/- and AT2-/- mice.